Cooking oils, such as those used in commercial or institutional deep fryers, tend to become contaminated with moisture, carbonized food particles, and the like during the frying process. Additionally, the oils themselves tend to break down chemically after extended use. Both the contaminants and the chemical breakdown byproducts have the undesirable characteristics of causing the oil to foam, smoke, smell bad, possess an unsightly appearance, or impart a bad taste to the fried food. It has been found that keeping the cooking oil clean by removing the particulate matter and filtering it on a regular basis tends to extend the useful life of the cooking oil and increase the quality and appearance of foods which are cooked therein.
Previous cooking oil filter media include wire mesh strainers, coarse paper, and diatomaceous earth or similar filtering material. Wire mesh strainers are restricted to the removal of large particulate matter. Conventional coarse paper filters (having a pore size of from 4 to 80 microns with a mean pore size on the order of 10 microns) exhibits only moderate filtering effectiveness. Diatomaceous earth and similar filtering materials usually exist in a loose form that is messy and awkward to handle. A further disadvantage common to all previous filters utilizing a covering of diatomaceous earth or other particulate filtering material is the nonuniformity of the thickness and pore opening of the particulate filtering material. Such nonuniformity causes the oil to principally pass through parts of the filter which are the least thickly covered with the particulate filtering material, thereby resulting in improper filtering. This tendency is further accentuated when the cooking oil is forced through the filter under positive pressure or vacuum, rather than by gravitational forces.
As a result, there has been a long-felt need for a cooking oil filter having substantially uniform thickness and a pore size that exhibits excellent filtering properties. Moreover there has been a continuing need for a filter exhibiting these characteristics that is relatively inexpensive and easy to handle. This invention is directed to satisfying this need.